1. Technical Field
The present technology relates generally to oilfield equipment. In particular, the present technology relates to hydraulic accumulators for use in oilfield applications.
2. Discussion of the Background
In the drilling industry, hydraulic controls are used for controlling many safety components. In addition, many such components are powered by hydraulic accumulators. To ensure safety, it is desirable to know whether an accumulator will have enough hydraulic fluid to fire a particular safety component. One way to determine the volume of fluid in a hydraulic accumulator is to determine the position of the piston within the accumulator.
Known methods of determining the amount of hydraulic fluid in an accumulator include the use of cable extension transducers, wherein a cable is physically attached to the piston in the accumulator. Based on the amount of cable pulled into the accumulator, the position of the piston in the accumulator can be determined. Use of cable extension transducers can be problematic because they require physical invasion into the accumulator and multiple mechanical parts working together, each of which leads to decreased reliability of the accumulator, and greater maintenance costs.
Another method of determining piston position within an accumulator includes use of acoustic signals transmitted into the accumulator. This method avoids physical intrusion into the accumulator by a cable, but has problems of its own. For example, to accurately determine distance through a medium using acoustic waves, certain properties of the medium must be known, such as temperature and pressure. Thus, temperature and pressure gauges need to be installed within the medium in the accumulator to determine these parameters. The introduction of additional sensors decreases reliability of the system, as well as the accuracy of information obtained regarding position of the piston.